Home › Guides › Guides & explainers

Common Medical Billing Errors and Where to Look for Each

Last reviewed 2026-11-02 · Guides & explainers

Short answerCommon medical billing errors include duplicate charges, upcoding, unbundling, balance billing, services not rendered, wrong patient or date, billing after insurance paid, charges for denied services, wrong quantities and facility fee confusion. Most are found by comparing an itemized bill with your EOB and your own notes from the visit.

How do you check a bill for errors?

You need three things side by side: an itemized bill, the EOB from your insurer, and your own notes about what happened. A summary statement is not enough, because errors hide inside totals. If you only have a summary, request an itemized bill first.

Read the bill once for the basics: your name, the dates, the provider. Then read it again line by line against the EOB.

Which errors involve the charges themselves?

These show up on the itemized bill. They are the easiest to catch if you read each line.

Duplicate charges: the same service or supply listed more than once on a date
Services not rendered: items or procedures you do not recall receiving
Wrong quantity or units: for example, three of an item when you received one
Wrong date or patient: charges dated outside your visit, or someone else's care
Upcoding: a higher service level than the care provided
Unbundling: billing separately for services that should be billed together under CMS correct-coding rules

Which errors involve insurance?

These appear when you compare the bill to the EOB. A balance that is higher than the EOB's patient responsibility is the first clue.

Providers sometimes bill you before the insurer has paid, or bill the full charge even though the EOB shows an adjustment. Others bill for a service the plan denied, or for a prior-authorization problem that was the provider's responsibility to handle.

Billed after insurance paid: your share was already covered or written off
Charges for denied or unauthorized services: ask whether the provider or the plan should bear the cost
Out-of-network billing at an in-network facility: may be covered by the No Surprises Act
Facility fee confusion: a hospital facility charge in addition to the doctor's fee, which you should be able to match to your visit

Where do clerical mistakes come from?

Typing and data-entry errors are common. A transposed digit can change an account number, a date or a code. Names that are similar can lead to a bill reaching the wrong patient. If a charge makes no sense at all, a clerical error is a reasonable first guess, and a call to billing may fix it in one conversation.

What do you do when you find one?

Mark it on your copy, call the billing office, and follow up in writing. Say exactly which line, which date and which amount. Ask for a corrected bill and a hold on collection while they review. Many providers and collectors expect disputes within a short window printed on the bill, so act promptly.

If the provider does not respond, go to your insurer, then to your state insurance department or attorney general. Medical Bill Dispute Pro scans an uploaded bill for possible errors in these categories and builds a letter from the ones you confirm, but you should review it before you send it.

Check your bill and get a dispute letter

Upload your bill. Our tool flags possible billing errors and drafts a formal dispute letter you can review and send.

Start my dispute letter — $29

🔒 Secure checkout · Flat $29, no percentage of savings · Satisfaction guaranteed (see terms)

Frequently asked questions

How do I know if a charge is wrong or just unfamiliar?

Ask the billing office what the line is, when it was provided and who ordered it, in writing if possible. Unfamiliar does not always mean wrong, since hospital stays include many small items. Compare it against your records and the EOB.

Do I need medical knowledge to review a bill?

Not for most checks. You can catch duplicates, wrong dates, wrong quantities and mismatches with the EOB without any medical training. For coding questions, ask the provider to explain, or consider a billing advocate.

What is the difference between upcoding and unbundling?

Upcoding is billing a higher level of a service than was provided, such as a higher emergency visit level. Unbundling is billing separately for services that should be billed together. Both raise the amount billed, and both can be questioned in a written dispute.

Can an error be in my insurer's processing instead of the bill?

Yes. The EOB may apply your deductible incorrectly or treat a provider as out-of-network. Call your insurer, ask for a reprocessing or appeal, and note that the appeal deadline is printed on your denial notice or EOB.

Where can I report a provider that keeps billing incorrectly?

Complaints about provider billing practices may go to your state attorney general's consumer protection office. Complaints about insurers go to your state insurance department. CMS also runs a No Surprises Help Desk at 1-800-985-3059 for covered situations.

Sources and further reading

Not legal or medical advice. Medical Bill Dispute Pro is a software tool that helps you prepare billing dispute letters. It is not a law firm, does not provide legal advice, and cannot guarantee any outcome. Laws and rules change and vary by plan and state; verify important details with the sources linked above, your insurer, or a qualified professional.